题目描述

blablabla

样例

blablabla

算法1

Java 代码

import java.io.*;

public class Main {

    private static BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
    private static final int maxSize = 100010;  // 数组最大容量
    private static int front = -1;           //  队列头
    private static int rear = -1;            // 队列尾
    static int[] q = new int[maxSize];                  // 数据规模为 10w

    // 入队
    public static void push(int val) {
        if(isFull()) return;
        q[++rear] = val;
    }

    // 出队
    public static int pop() {
        return q[++front];
    }

    // 判断队列是否为空
    public static boolean empty() {
        return front == rear;
    }

    public static boolean isFull() {
        return rear == maxSize-1;
    }

    // 查询队头元素
    public static int query() {
        return q[front+1];
    }

    // 查询队尾元素
    public static int queryToTail() {
        return q[rear];
    }

    // 程序入口
    public static void main(String[] args) throws IOException {
        int m = Integer.parseInt(reader.readLine());

        while (m-- > 0) {
            String[] s = reader.readLine().split(" ");
            if (s[0].equals("push")) {
                push(Integer.parseInt(s[1]));
            } else if (s[0].equals("pop")) {
                pop();
            } else if (s[0].equals("query")) {
                System.out.println(query());
            } else {    // s[0].equals("empty")
                if (empty()) System.out.println("YES");
                else System.out.println("NO");
            }
        }
    }
}